This invention relates to wire drawing dies.
One type of wire drawing die consists of a cemented carbide ring enclosing an abrasive compact to which it is bonded. A hole extending axially through the abrasive compact is provided and the wire to be drawn is pulled through this hole. In use, the cemented carbide support ring is held in a metal surround.
The abrasive compacts which are used in such dies are known in the art and consist essentially of a mass of abrasive particles present in an amount of at least 70 percent, preferably 80 to 90 percent, by volume of the compact bonded into a hard conglomerate. Compacts are polycrystalline masses and can replace single large crystals in many applications. The abrasive particles of compacts are invariably ultra-hard abrasives such as diamond and cubic boron nitride.
The abrasive compacts which have generally thus far been used in wire drawing dies contain a second phase or bonding matrix which contains a catalyst (also known as a solvent) useful in synthesising the particles. In the case of cubic boron nitride, examples of suitable catalysts are aluminium, or an alloy of aluminium with nickel, cobalt, iron, manganese or chromium. In the case of diamond, examples of suitable catalysts are metals of Group VIII of the Periodic Table such as cobalt, nickel or iron or an alloy containing such a metal.